In industrial production systems field devices are in use as a rule in a wealth of positions which can be remotely controlled or operated from a central location via a field bus. "Field devices" is the general term designating sensors and actuators employed in systems in which industrial processes are run. Such field devices may be pressure gauges with the aid of which the pressure in a container can be measured and monitored. However, temperature gauges may also be involved with the aid of which the temperature can be monitored at a desired location in the process sequence. A level sensor may also be put to use as a field device for monitoring the level in a container. Increasing use is being made of smart devices as field devices which offer substantially more possibilities of application than more conventional devices for data acquisition. Smart field devices are capable of not only processing the acquired data, they also make it possible to engineer the parameters of the field devices with the aid of e.g. a pc-based controller incorporated at the central location or also by means of a portable controller via the field bus in on-line or even off-line operation. For example, depending on the requirements a variety of design data values or also limiting values of measuring data as well as range data values can be transmitted via the field bus to the field devices. To achieve this functionality a description of the field device parameters is required for the application program stored in the field device. This description can be viewed as an eighth layer of the OSI layer model created as a standard description of a network architecture for which various so-called device description languages (DDLs) are defined which can be employed for this purpose. These device description languages describe not only the attributes of the field device parameters but also the dependencies or relationships between the parameters and attributes.
However, the approach described hitherto for remote control and remote operation of field devices by working with device description languages has numerous drawbacks. There is no assurance that the device description (DD) produced for a field device in using one of the languages correctly describes the functionality of the device. For complex field devices it is extremely difficult to produce a device description which is consistent with the functionality of the parameters of the field device, there being to date no tool available with the aid of which the device code can be converted into a device description or for producing the device code from a device description. Device description languages exist in great variety, specific to certain controllers, this meaning that a dedicated device description needs to be written for each combination of field device and controller. As soon as a new device is to be put to use or the software of an existing device needs to be updated this usually involves the device description needing to be updated which then has to be transferred to the controller. This is usually done by entering the updated device description into the controller with the aid of a diskette which can easily lead to version problems.
A simplified example of an assembly of the aforementioned kind is shown in FIG. 1. The field device 101 is provided with a memory 102 in which a processor-specific binary code is stored. This binary code is generated usually with the aid of an assembler/C source code from one or more data files 103 and processing in an assembly, a compiler and a linker, these programs being dictated in a block 104. In the field device 101 the binary code is then processed in a suitable processor 105. The controller 108 connected to the field device 101 via the field bus 106 consists of a universal part designated the DD shell and work surface 109. In addition the controller contains a flexible field device specific part 110 into which the DD code can be entered. This DD code represents the functionality specific to the field device in each case. The DD code is e.g. a dynamic link library (DLL), and is entered into the flexible part 110 via a diskette 113. The DD code is generated by a DD compiler 112 operating with application of one or more DD source data files 111. The transmission of the device parameters between the field device 101 and the controller 108, as indicated by the arrows 107, is handled by the field bus 106.